1. Field of the Invention
The present invention relates to an image processing apparatus. More particularly, the present invention relates to a technique of extracting visual information (e.g., character information), from a region (blank) printed on a sheet in a dropout color that can be discriminated by man, but cannot be discriminated by an optical reading apparatus.
2. Description of the Related Art
For example, as shown in FIGS. 1a to 1c, character information to be read by an optical character reading apparatus (hereinafter referred to as an OCR) is generally filled in a frame region (blank) 3 in a dropout color which can be discriminated by man, but cannot be discriminated by the apparatus, on a sheet 1 (see FIGS. 1a, 1b). A read sensor in the OCR discriminates character information (in the illustrated example, "10000") filled in the sheet 1 from the frame region (blank) 3 based on the difference in color therebetween, carries out a so-called dropout processing for removing the frame region 3, and thus extracts image information including only character information (see FIG. 1c). Further, the extracted image information is subject to a pattern recognition processing.
Conventionally, in a known OCR, a region, which is an object of pattern recognition on a sheet in which character information to be read is filled, has been determined based on criterion of the regular direction and position in a reading of the sheet. Accordingly, where the sheet is read with being greatly inclined with respect to the regular read direction, or where the sheet is greatly displaced with respect to the regular position, a problem occurs in that a precision in extraction of character information or image information filled in a frame region is lowered, and thus the degree of recognition of the character information in the pattern recognition is lowered.
Also, regarding the above sheet, respective high precisions are demanded in a production of the sheet with respect to a shape and uniformity of a color of the sheet, and with respect to a shape, dropout color, and a position of a frame region to be printed. Also, in a storage of the sheet, it is required to pay attention to preventing the respective precisions from being deteriorated due to sunlight or other conditions. To this end, problems occur in that a running cost and a management cost pertaining to the sheet are increased, and in that it is impossible to flexibly cope with the variety of print colors and colors of character information to be filled.
Furthermore, where a reading of a sheet into which character information and image information such as photographs are incorporated, e.g., a reading of a catalog, is carried out, a problem occurs in that it is impossible to normally execute a dropout processing. This is because information with the same color as that of the character information, or with the same color as the dropout color, is included in the image information. As a result, a disadvantage arises in that time required for the operation processing in the pattern recognition is prolonged, and thus the degree of recognition is lowered. Such a disadvantage can be removed, for example, by effecting a processing of masking unnecessary image information such as photographs, prior to the pattern recognition processing. However, since such a masking processing is realized using a complicated operation processing, it cannot always apply to an ordinary work using an OCR, in view of restrictions of the response and cost.